High-availability displacement sensing with multi-channel self mixing interferometry

Laser self-mixing is in principle a simple and robust general purpose interferometric method, with the additional expressivity which results from nonlinearity. However, it is rather sensitive to unwanted changes in target reflectivity, which often hinders applications with non-cooperative targets. Here we analyze experimentally a multi-channel sensor based on three independent self-mixing signals processed by a small neural network. We show that it provides high-availability motion sensing, robust not only to measurement noise but also to complete loss of signal in some channels. As a form of hybrid sensing based on nonlinear photonics and neural networks, it also opens perspectives for fully multimodal complex photonics sensing

Coronal Imaging with the Solar Ultraviolet Imager

Coronal imaging capabilities of the Solar UltraViolet Imager (SUVI) on the Geostationary Operational Environmental Satellite-16 (GOES-16) are investigated. Launched in 2016, GOES-16 is stationed at 75.2 deg W longitude and accommodates both terrestrial and space weather instruments. SUVI is one of two instruments observing the Sun, providing solar images in six extreme ultraviolet (EUV) wavelengths: 94A, 131A, 171A, 195A, 284A and 304A. Mounted on a two axis gimballed Sun Pointed Platform (SPP), its 53 arc minute square field of view is nominally Sun-centered to provide high dynamic range images in all six wavelengths every four minutes. Analyses of on-orbit data indicated that SUVI had sufficient dynamic range and sensitivity in the 171A and 195A wavelengths to image the corona to the largest heights above the Sun to date while simultaneously imaging the Sun. The 1.6 megapixel Charge Coupled Device (CCD) detector enables the capture of the fine features of the corona. On-orbit calibration tests requiring movement of the SUVI line-of-sight off the Sun, demonstrated that the resulting dynamic disturbance didn't adversely impact the earth-pointing instrument performance. Combining these factors, we conducted a test to assess the performance of SUVI as an EUV extremely wide-field coronal imager by off-pointing the SPP around the Sun and synthesizing an image that's about 4 times the diameter of the Sun. The capability to perform coronal imaging at these two wavelengths is demonstrated by off-pointing the SUVI boresight to nine locations around the Sun and generating a composite coronal image that extends to approx. 4 solar radii. For this purpose, we exploited the satellite's ability to provide stable, fine pointing, even during the slews. Various exposure durations were considered during the first trial and a composite coronal image is obtained for each wavelength. The results are promising. The off-pointing locations and the exposure duration are being refined for the subsequent trials. The routine use of an ultraviolet solar imager as both an imager and a EUV coronagraph would be the first of its kind and is an exciting development. The on-orbit solar coronagraphs to date provide white light images with fields of view extending from 4-15 solar radii. Earlier, Seaton, et al investigated the evolution of the corona in EUV near the solar surface with the data from the Sun Watcher with Active Pixels and Image Processing (SWAP) EUV solar telescope on board the Project for On-Board Autonomy 2 (PROBA2). The presence of corona in EUV even to 4 solar radii is not known. The results of these experiments will begin to fill this void

Olfactory functions assessment of the mouse model of the human 22q11.2 deletion syndrome

Schizophrenia is a neuropsychiatric disease with 1% prevalence in the population. Patients affected by this disorder suffer from negative symptoms such as alogia or avolition; and from positive symptoms such as hallucinations or delusions. Cognitive disabilities such as working memory and language function deficits have often been indexed in Schizophrenia’s symptomatology. Even though its symptoms are well known, the etiology of Schizophrenia remains unclear. However, the discovery of the Velo-Cardio-Facial syndrome (VCFS) put one step further in understanding the mechanism of the disease. Indeed, a deletion on the chromosome 22 in the q11.2 band causes this syndrome and one of its most common symptoms is Schizophrenia. Since then, a quasi-perfect synteny between one part of the 22q11.2 region in humans and the chromosome 16qA3 has been discovered and several mouse model of the VCFS form of Schizophrenia have been engineered. In my thesis, the olfactory performances of LgDel+/- mice, one of several murine model of the human 22q11.2 deletion, have been studied. Indeed, idiopathic schizophrenics as well as VCFS patients show olfactory deficits such as olfactory hallucinations or olfactory identification and discrimination impairments. During my project, we could find that odorant detection is intact in mutant mice using functional imaging. Behavioral experimentations with an olfactometer allow testing primary olfactory discrimination as well as detection threshold and rule flexibility. None of them are impaired in LgDel+/- mice however; using also the olfactometer, there are strong presumptions suggesting that attention and olfactory memory seem to be defective in LgDel+/- mice

Quel statut pour les derniers occupants de la villa du Moulin de chez Bret à Jonzac (Charente-Maritime, France) ?

International audienc

Quel statut pour les derniers occupants de la villa du Moulin de chez Bret à Jonzac (Charente-Maritime, France) ?

National audienc

Realization and Numerical Simulation of a High Power and High Efficiency Holmium Doped Fiber Laser at 2.1 μm

International audienceHolmium fiber lasers pumped in-band with Tm fiber lasers appear as interesting solutions when looking for high power in a single spatial mode and high electro-optic efficiency, in a spectral domain that guarantees eye-safe emission and low absorption by the atmosphere. We will present the progress of our work on a high efficiency holmium (Ho) fiber laser, detailing the numeric model, experimental realization and results